1. Field of the Invention
The present invention relates to a printer system including a printer driver for generating printer data from data on an object to be printed, and a printer for executing the printing of the printed object on the basis of the printer data. More particularly, the invention relates to a printer system including a printer driver capable of adding attribute information to the printer data and a printer capable of extracting the added attribute information from the printer data.
The present application is based on Japanese Patent Application No. Hei. 2000-336027, which is incorporated herein by reference.
2. Description of the Related Art
FIG. 6 is a block diagram showing a conventional printer system including host computer for sending a print request, and a printer for executing the printing in response to the print request. To execute the printing as instructed from the host computer 1, usually, the user first operates an application software 2 installed to the host computer 1 to enter necessary commands, such as formation or select of an object to be printed, e.g., images, characters, graphics, and a print request to request the printing of the printed object. In a simple example of this, the user forms a document by using a document processing software, and prints the document.
When a print command is issued, a process is executed under control of the application software 2, and data of objects (characters, images, graphics) contained in the printed object is transferred to a printer driver 3 installed to the host computer 1. The printer driver 3 is a software program which functions as an interface between the host computer 1 and the printer 5, and provided for each type of printer 5. The printer driver develops the data of the printed object as received into image data for the printer 5 associated with the printer driver. Specifically, the printer driver forms data consisting of a list of color information pieces each for one dot on a page to be printed (This data will be referred to as printer data.). In the color printing, the color information for each dot consists of color data of respective colors (C, M, Y, K or R, G, B).
Then, the printer data thus formed is transmitted through a transmission path 4, e.g., LAN (local area network), to the printer 5, and the printer 5 executes the printing of the printer data. In the printer 5, the controller 6 receives the printer data, and image processes the printer data (e.g., binarizes the printer data) into print commands for transfer to a print engine 7 for actually executing the printing, and issues the print commands in synchronism with the operation of the print engine 7. The print engine 7 operates in accordance with the print commands to execute the printing of the object to be printed.
By convention, the printing as instructed from the host computer 1 is executed by the system configuration and processing contents as mentioned above.
To execute the printing as instructed from the host computer 1, as described above, the color information pieces each for one dot are transmitted from the printer driver 3 to the controller 6 of the printer 5. To print by the color printer, the color data of the respective colors and given attribute information that is added for each dot to the printer data as well are frequently transmitted to the printer 5. In a case where dots to be printed are contained in the character and a case where those are contained in the image, even if the color information (color data of the respective colors), which are used for those cases, are one and the same, it is necessary to modify the binarizing process and the color conversion process, which are carried out by the controller 6, in order to secure an attractive print quality. This necessitates the transmission of image processing information (attribute information) used for the process modification, together with the color information, to the controller 6.
The color data is usually expressed by using 8 bits (0 to 255) per one color (one element). Accordingly, the color information is represented by using 32-bit data when it is expressed in terms of C, M, Y, K, and by using 24-bit data when it is expressed in terms of R, G, B. Other kinds of information are also expressed by using the data of 8 bits long.
Accordingly, in a case where the attribute information must be added to the printer data, when the attribute information is added to the 32-bit or 24-bit data of the color information, it must take the form of 8-bit data even if it consists of 1 bit. This results in increase of the amount of printer data. Hence, the load is increased in the transfer of data from the host computer 1 to the printer 5 and the data storage in the printer 5.